Palestinian President Mahmoud Abbas has signed a document at a meeting in Ramallah requesting membership of the International Criminal Court (ICC).
Abbas signed the document on Wednesday, a day after a UN Security Council (UNSC) failed to pass a resolution that had aimed to set a deadline for Israel to end its occupation of territories sought by the Palestinians.
The president also signed a raft of about 20 other treaties, aligning Palestine with various international organizations.
The decision sets the stage for filing a war crimes case against Israel for its actions in Gaza. Israel's President Benjamin Netanyahu vowed to take action following the announcement.
The signed statute will now be passed to the UN's secretary-general, Ban Ki-moon, who will consider the application to join the ICC.
While not guaranteed, legal experts think the process is likely to result in Palestinian membership being approved.
"The one who needs to fear the International Criminal Court in The Hague is the Palestinian Authority, which has a unity government with Hamas, a terror organization like [ISIL] which commits war crimes," Netanyahu said in a statement.
"Israel will respond and defend the soldiers of the IDF [the Israeli army] the most moral army in the world.
"We will rebuff this effort to impose a diktat on us, just as we rebuffed the Palestinian efforts in the UNSC."
'Retroactive investigation'
US State Department spokesman Edgar Vasquez said Washington strongly opposed the move and warned it would be "counter-productive and do nothing to further the aspirations of the Palestinian people for a sovereign and independent state."
Al Jazeera's diplomatic editor James Bays said the Palestinians had been threatening to sign the Rome Statute for a long time, but had been afraid of the negative response from the United States.
"This could pave the way for things that have happened in Palestinian territory and Israel being taken to the ICC," he said.
"Potentially Israeli leaders and Palestinian leaders could find themselves in court.
"They can ask for [ICC] investigations, not just from day they signed the statute, but a retroactive investigation into past events.
"There are some legal doubts as to what will be covered, but most legal experts believe fighting in Gaza this summer could be included."
International allegiances
Abbas had warned that if the UN resolution failed, he would resume a Palestinian campaign to join international organizations to put pressure on Israel.
Abbas' decision is expected to trigger a harsh response from Israel.
Israel says all disputes should be resolved through peace talks, and such actions are aimed at bypassing negotiations.
Al Jazeera's Imtiaz Tyab, reporting from Ramallah, said that people were expecting President Abbas to standby his pledges.
"People here wanted a muscular response from the president, and he has made good on his promises as to what would happen if the resolution failed."
PHOTO CAPTION
Palestinian President Mahmoud Abbas speaks during a leadership meeting in the West Bank city of Ramallah .
Aljazeera